Intermolecular π/π and H/π interactions in dimers researched by different computational methods

The analysis of π/π and H /π interactions in complexes are a challenging aspect of theoretical research. Due to the different approximations of different levels of theory, results tend to be inconsistent. We compared the reliabilities of HF, SVWN, M06L, PW91, BLYP, B3LYP, BHandHLYP, B97D, MP2, and DFTB-D approaches in researching π/π and H /π interactions by calculating the binding energies of five benzene-containing dimers. The effects of 6-31+G**, 6-311++G** and 6-311++G(2df,2p) basis sets on the results were analyzed too. We found that the DFTB-D and B97D methods combined with the 6-311++G** basis set perform well for dimers that contain π/π and H /π interactions. With high efficiency and satisfactory precision, DFTB-D is helpful for the calculation of complexes containing π/π and H /π stacking. We further calculated the structures and properties of phenylalanine-containing dimers using the DFTB-D and B97D methods. The properties of low energy conformers such as rotational constants, dipole moments and molecular orbitals were also analyzed. These data should be helpful for research into systems that contain π/π and H /π stacking.